1. Field of the Invention
This invention relates to the field of catheters and analyte and therapy sensors used in biomedical applications and, in particular, to a catheter having multiple lumens and a process of making and using the same and to analyte and therapy sensors used in critical care situations.
2. Description of Related Art
The accurate and timely monitoring of vital signs and other biomedical or physiological parameters in a critical care or intensive care setting can often mean the difference between success and disaster for patients and the medical care providers rendering treatment for those patients. For such patients, the quality of life and, possibly, even life itself may depend on such monitoring.
Some types of physiological parameter monitoring, while critical, have traditionally been slow and cumbersome. For example, for patients who are in an intensive care environment, especially those with diabetes, glucose monitoring is critical. If the amount of glucose in a patient's system is not maintained at proper levels, the patient may sustain serious or life-threatening injury. If too much glucose accumulates in the patient's system, the patient could become hyperglycemic, resulting in shortness of breath, nausea and vomiting at best or coma and death in the worst case. If there is too little glucose in the patient's system, the patient could become hypoglycemic, resulting in dizziness, sweating and headache at best and unconsciousness and death in the worst case.
Glucose monitoring in a critical care or intensive care environment has typically been done manually. For example, in some facilities, if a patient with diabetes is in a critical or intensive care environment, a medical care provider draws a sample of blood from the patient and sends it to a lab, hopefully on site, for glucose analysis. Based on the results of the analysis, the patient is treated accordingly, possibly with insulin or glucose infusion depending on whether the patient is hyperglycemic or hypoglycemic, respectively. This process, i.e., drawing a sample of blood from the patient, transferring the blood to a laboratory for analysis, transferring the results of the analysis back to the patient's medical care provider, reviewing the analysis, recommending a suitable treatment, and administering the treatment, can be cumbersome and is prone to human error.
Ideally, and for the benefit of the patient, the time between admission of the patient to the critical or intensive care ward to the time of drug infusion and stabilization of blood glucose levels is minimal. However, given the nature of laboratory diagnostics and manual analysis, the time lag from patient admission to glucose analysis and, ultimately, to treatment is sometimes longer than desirable.
In addition, for treatment to be rendered to the patient, one or more catheters may be inserted into the patient's body. For example, if treatment of the patient necessitates infusions of blood and insulin, blood and drugs, blood and glucose or the like, traditional caregivers have placed two separate catheters into the patient's body and connected each catheter to an appropriate infusion delivery system. For each catheter used, a separate catheter tunneling procedure must be performed, which can be very uncomfortable for the patient physically. Moreover, for each catheter exiting the patient's body, the risk that a catheter is disturbed, accidentally displaced or otherwise interfered with increases. Also, multiple catheters can increase the risk of infection.
Over the years, bodily characteristics have been determined by obtaining a sample of bodily fluid. For example, diabetics often test for blood glucose levels with a blood glucose meter. Traditional blood glucose determinations have utilized a painful finger prick using a lancet to withdraw a small blood sample that is used by the blood glucose meter. However, in critical care situations, these discrete blood meter readings are inefficient in closely monitoring blood characteristics since they would need to be taken every minute to provide near continuous data required during critical care situations.
Long-term implanted sensors have been proposed that can stay in the body for long periods of time, such as weeks and months. These long-term implanted sensors are particularly well adapted in delivering dependable data over a period of time as well as detecting immediate changes in blood characteristics since they are implanted in one of the main arteries near the heart. However, these sensors need to be implanted in a separate procedure, often not feasible for critical care patients. Moreover, although an implanted sensor (e.g. a glucose sensor) may make sense for diabetic patients needing long term care of the disease, non-diabetic patients may not need a long-term implanted sensor outside the intensive care unit.